The Bush administration is reportedly stepping up pressure on foreign energy companies to limit their investments in Iran, especially now that the West is in a dispute with Tehran over Iran's nuclear programme and the US believes Iran is helping insurgents in Iraq.

The US has had a law on the books since 1995 that threatens foreign energy companies that invest more than $20 million a year in Iran. A handful of big companies have invested that amount, but the US has never sanctioned any companies under the law.

Nonetheless, Daniel Sullivan, US Assistant Secretary of State for Economic, Energy and Business Affairs, discussed the law with Norwegian Energy Minister Odd Roger Enoksen.

Sullivan "pointed out the US view on the Iran case, and investments from the Norwegian companies in this region," Enoksen told reporters following a speech at the Center for Strategic and International Studies think tank, Reuters reported.

"We do not support unilateral sanctions toward Iran," Enoksen said of the US law. "This is a commercial decision that has to be made by Norwegian companies."

Norway's oil group Statoil said in a filing this month with the US Securities & Exchange Commission that it could face US sanctions because of the company's 2002 deal to help develop Iran's South Pars natural gas project.

Statoil has 37%of the South Pars license and had invested $394 million in the project by the end of last year.

Enoksen said Sullivan did not specifically ask that Norwegian energy companies stay out of Iran, nor did he indicate that the Bush administration would impose financial sanctions on companies that violated the US law.

"They just wanted to inform me of the US government's view on the situation in Iran," Enoksen said.

Published: 28 March 2007 22:14 GMT  | Last updated: 29 March 2007 08:10 GMT